Field
The present disclosure generally concerns prosthetic heart valves and associated devices and related methods for implanting such devices. More specifically, the disclosure relates to the repair and replacement of heart valves that have malformations and/or dysfunctions, where an additional dock or anchor is utilized together with the prosthetic heart valve at the implant site, and methods of implanting such anchors and/or prosthetic heart valves.
Description of Related Art
Referring generally to FIGS. 1A-1B, the native mitral valve controls the flow of blood from the left atrium to the left ventricle of the human heart. The mitral valve has a very different anatomy than other native heart valves. The mitral valve includes an annulus made up of native valve tissue surrounding the mitral valve orifice, and a pair of cusps or leaflets extending downward from the annulus into the left ventricle. The mitral valve annulus can form a “D” shaped, oval shaped, or otherwise non-circular cross-sectional shape having major and minor axes. An anterior leaflet can be larger than a posterior leaflet of the valve, forming a generally “C” shaped boundary between the abutting free edges of the leaflets when they are closed together.
When operating properly, the anterior leaflet and the posterior leaflet of the mitral valve function together as a one-way valve to allow blood to flow only from the left atrium to the left ventricle. After the left atrium receives oxygenated blood from the pulmonary veins, the muscles of the left atrium contract and the left ventricle dilates (also referred to as “ventricular diastole” or “diastole”), and the oxygenated blood that is collected in the left atrium flows into the left ventricle. Then, the muscles of the left atrium relax and the muscles of the left ventricle contract (also referred to as “ventricular systole” or “systole”), to move the oxygenated blood out of the left ventricle and through the aortic valve to the rest of the body. The increased blood pressure in the left ventricle during ventricular systole urges the two leaflets of the mitral valve together, thereby closing the one-way mitral valve so that blood cannot flow back into the left atrium. To prevent the two leaflets from prolapsing under the pressure and folding back through the mitral annulus toward the left atrium during ventricular systole, a plurality of fibrous cords called chordae tendineae tether the leaflets to papillary muscles in the left ventricle.
One common form of valvular heart disease is mitral valve leak, also known as mitral regurgitation. Mitral regurgitation occurs when the native mitral valve fails to close properly and blood flows back into the left atrium from the left ventricle during the systolic phase of heart contraction. Mitral regurgitation has different causes, such as leaflet prolapse, dysfunctional papillary muscles, and/or stretching of the mitral valve annulus resulting from dilation of the left ventricle. In addition to mitral regurgitation, mitral narrowing or stenosis is another example of valvular heart disease.
Like the mitral valve, the aortic valve is susceptible to complications such as aortic valve stenosis. One method for treating such valvular heart disease includes the use of a prosthetic valve implanted within the native heart valve. These prosthetic valves can be implanted using a variety of techniques, including various transcatheter techniques. One transcatheter technique that is commonly used for accessing a native valve is the transseptal technique, where a catheter accesses the left side of the heart via a femoral vein, the inferior vena cava, the right atrium, and then a puncture hole in the interatrial septum. A prosthetic valve can then be mounted in a crimped state on the end portion of a second, flexible and/or steerable catheter, advanced to the implantation site, and then expanded to its functional size, for example, by inflating a balloon on which the valve is mounted. Alternatively, a self-expanding prosthetic valve can be retained in a radially compressed state within a sheath of a delivery catheter, and the prosthetic valve can be deployed from the sheath, which allows the prosthetic valve to expand to its functional state.
Another common transcatheter technique for implanting a prosthetic valve is a transventricular approach, where a small incision is made in the chest wall and the ventricular wall of a patient, and then a catheter or introducer sheath is inserted into the left ventricle. A delivery catheter containing or holding the prosthetic valve can then be advanced through the introducer sheath to the implantation site.
Such prosthetic valves are generally better developed for implantation or use at the aortic valve. However, similar catheter-based prosthetic valves can be more difficult to apply or implant at the native mitral valve due to the structural differences between the aortic and mitral valves. For example, the mitral valve has a more complex subvalvular apparatus, which includes the chordae tendineae. Additionally, the native mitral valve is less circular in shape and typically does not provide sufficient structure for anchoring and resisting migration of a prosthetic valve.